Make shale and take Quiz 3

 Compare your two sandstone samples and your shale sample.  How are the alike?  Both composed of particles  Both sedimentary rock  How are they different?  Sandstone is rough  Shale is smooth, made with smaller particles

 The sediments from the stream table are smooth.  It is composed of clay, silt or both  Silt and clay were carried much farther in our stream table than the sand, because they are so small.

 How did the clay and silt get so small?  A rock would have to get smashed around a great deal to get that small. They must have traveled and or weathered a great deal.  Where do we find silt and clay in nature? Near or far from the source?  Far  What size particles would you find in slow moving or still water?  Small

 What size particles should we use for shale?  Silt or clay  What happens to wet clay of it dries out?  It hardens  Water can be removed 2 ways  It dries out when water retreats  It gets squeezed out due to compaction

 Sandstone is a mixture of sand and a matrix such as silica.  Shale has small particles like silt and clay and the water has been removed.  Normally shale forms when the clay dries out and hardens and does not require a matrix.  We do not have millions of years to wait, so we are adding plaster of paris to our mixture.  We find shale in places where there is slow moving water like edges of rivers, swamps, lakes and ponds.

 3 heaping spoons of clay  2 heaping spoons of plaster of paris  30 mL of water  Mix clay and plaster  Add water. It should be thick like cookie dough. Add more water if needed. Don’t add too much!  Spoon on top of sandstone.  Clean cup and spoon as you did with the sandstone.